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physics paper thoughts if anyone remembers. (1 Viewer)

iSplicer

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this was such a bad question imo. poorly explained. the way they describe it in the question makes it impossible to answer (with or without slingshot effect)...and i know this is what the question was getting at by saying use kepplers laws to show how the doesnt make sense but researching it, the JWST travels in an elliptical orbit and the question makes out like it travels in a circular orbit.

the fact of the matter is that the slingshot effect isnt strong enough to account for its orbit. it is rather the coupling of the slingshot effect with an elliptical orbit. gay ass question. astrophysics students were so fucking advantaged in this test.
As an astrophysics student, let me assure you that we were not advantaged in any way.

I think I completely screwed up that question; i didn't mention anything about langrage points or the gravitational effect of the earth, as these are completely out of the syllabus and I had no idea how to include Kepler's law in explaining langrangian mechanics. I based my answer completely on Kepler's law of periods linked with the concept of center of mass (when considering the barycenters, the 'r' variable may indeed be the same --> same period). Did anyone else do this?
 

Jonneeh

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Q24 is the slingshot effect.

ie. Indeed it appear that Kepler's laws are being violated as r^3/T^2 is a constant value and 'r' is greater for the JWST. But JWST orbits near the Earth and so experiences gravitational attraction towards the Earth (as Earth has a much greater mass than the JWST). So it orbits with the same period as the Earth.

Good question. I like it. A good novice seperator.
Yay i wrote that lols
 

susanpowell

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"the JWST will orbit the Sun around L2, avoiding any part of Earth's shadow ... normally, an object circling the Sun further out than the Earth would take more than one year to complete its orbit. However, the balance of gravitational pull at the L2 point means that Webb will keep up with the Earth as it goes around the Sun."

no where does it mention that it
(a) orbits around the earth
(b) uses the slingshot effect
 

cutemouse

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"gravitational pull at the L2 point". That is the slingshot effect.
 
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As an astrophysics student, let me assure you that we were not advantaged in any way.

I think I completely screwed up that question; i didn't mention anything about langrage points or the gravitational effect of the earth, as these are completely out of the syllabus and I had no idea how to include Kepler's law in explaining langrangian mechanics. I based my answer completely on Kepler's law of periods linked with the concept of center of mass (when considering the barycenters, the 'r' variable may indeed be the same --> same period). Did anyone else do this?
I did this and I do astro as well. I simply had no idea what the shit was going on for that Q lol...
 

Physics_FTW

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As an astrophysics student, let me assure you that we were not advantaged in any way.

I think I completely screwed up that question; i didn't mention anything about langrage points or the gravitational effect of the earth, as these are completely out of the syllabus and I had no idea how to include Kepler's law in explaining langrangian mechanics. I based my answer completely on Kepler's law of periods linked with the concept of center of mass (when considering the barycenters, the 'r' variable may indeed be the same --> same period). Did anyone else do this?
Gravitational effect of the Earth out of the syllabus? I dunno about that.

I reckon if you say something about seeing as it is close to the Earth, then there is the influence from the Earths gravitational field aswell as the influence from the Suns gravitational field, and the combination of these two gravitational fields provides the exact centripetal force required to rotate in unison with the Earth.

Seeing as Grav force is increased and therefore centripetal force is increased (as they are balanced), then you can solve these simultaneously and say that the orbital velocity will be greater than it would be if considering the grav field of the Sun alone, therefore it will be travelling faster than expected and appear to violate K3L.

Something along those lines should be acceptable?!?! I looked through the syllabus and yeah.. no mention of lagrangian points
 
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